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StarUML vs Mermaid: catalog facts
StarUML	Mermaid
Paid Commercial software; see the website for licence options.	Free Free and open source under the MIT licence.
macOS	Web, Command line
Covers most UML 2 diagram types Mixes UML, ERD, SysML, BPMN and more in one project	Diagrams are plain text, so they diff and review like code Rendered natively by GitHub, GitLab and most documentation generators
Commercial licence Closed source	Layout is automatic, so fine control over positioning is limited Complex diagrams become hard to read in source form
Downloadable app	Web application, Downloadable app
Closed source	Open source
License not stated	License: MIT
Not stated if an account is needed	Not stated if an account is needed
Works offline	Not stated if it works offline
Official website Full listing and sources Checked October 1, 2026	Official website Full listing and sources Checked September 22, 2026

Catalog facts only. Anything “not stated” is unconfirmed. Check full listings for details.